Faculty Bibliography

Quantitative Thermotesting evaluates peripheral small nerve fiber function. The method of limits is a widely used algorithm of perception threshold determination. Normative data are needed to apply the method of limits in children and juveniles. In 225 healthy boys and girls, aged 7 to 17.9 years, warm and cold perception thresholds were established with the method of limits at the volar distal forearm, the thenar eminence, the lower medial calf, the lateral dorsal foot, and the cheek. A 1 degree C/s stimulus velocity, a 32 degrees C thermode baseline, and a 1.5-cm x 2.5-cm Thermotest stimulator were used. Accuracy of stimulus perception was studied by comparing the lowest to the highest response of five consecutive stimuli. The influence of different stimulator sizes on thresholds was tested at the lower calf and distal forearm with an additional 2.5-cm x 5.0-cm thermode. To determine the impact of the pretest skin temperature on thresholds, skin temperature was correlated with thresholds. Results showed good intratrial reproducibility of thresholds. The large thermode yielded lower thresholds than the small probe. Skin temperature had only minor influence on thresholds. The large probe should be used at body sites where it adjusts planely

BACKGROUND: Many polyneuropathies manifest autonomic disturbances. Diabetic neuropathy, the most frequent neuropathy in the western world, serves as model of the symptomatology of autonomic disturbances. DIABETIC NEUROPATHY: Clinical symptoms comprise pupillary and cardiovascular dysfunction such as orthostatic hypotonia and syncopes, thermoregulatory, gastrointestinal symptoms, disturbances in urogenital and respiratory function and unawareness of hypoglycemia. OTHER NEUROPATHIES: This article also describes autonomic symptoms in alcoholic neuropathy, in Guillain-Barre syndrome, in paraneoplastic polyneuropathies, in toxic neuropathies, in acute and subacute autonomic neuropathy, in amyloidosis, in porphyria, in familiar dysautonomia, in HIV infection and in botulism

OBJECTIVE: Patients with familial dysautonomia have an increased risk of sudden death. In some patients with familial dysautonomia, sympathetic cardiac dysfunction is indicated by prolongation of corrected QT (QTc) interval, especially during stress tests. As many patients do not tolerate physical stress, additional indices are needed to predict autonomic risk. In familial dysautonomia there is a reduction of both sympathetic neurons and peripheral small nerve fibres which mediate temperature perception. Consequently, quantitative thermal perception test results might correlate with QTc values. If this assumption is correct, quantitative thermotesting could contribute to predicting increased autonomic risk. METHODS: To test this hypothesis, QTc intervals were determined in 12 male and eight female patients with familial dysautonomia, aged 10 to 41 years (mean 21.7 (SD 10.1) years), in supine and erect positions and postexercise and correlated with warm and cold perception thresholds assessed at six body sites using a Thermotest. RESULTS: Due to orthostatic presyncope, six patients were unable to undergo erect and postexercise QTc interval assessment. The QTc interval was prolonged (>440 ms) in two patients when supine and in two additional patients when erect and postexercise. Supine QTc intervals correlated significantly with thermal threshold values at the six body sites and with the number of sites with abnormal thermal perception (Spearman's rank correlation p<0.05). Abnormal Thermotest results were more frequent in the four patients with QTc prolongation and the six patients with intolerance to stress tests. CONCLUSION: The results suggest that impaired thermal perception correlates with cardiac sympathetic dysfunction in patients with familial dysautonomia. Thus thermotesting may provide an alternative, albeit indirect, means of assessing sympathetic dysfunction in autonomic disorders

Impaired vibratory perception is an early and frequent finding in various neuropathies. Quantitative vibratory threshold assessment refines the diagnosis of neuropathies but is based on psychophysical techniques requiring patient cooperation. Large, age and sex matched normative data bases are needed to better identify abnormal vibratory perception. In this study vibratory perception was tested at the second metacarpal bone and above the first metatarsal bone of 530 children, juveniles and adults aged 3.3-79.2 years. Thresholds assessed with a 128 Hz graded Rydel-Seiffer tuning fork, TF, were compared to three Vibrameter values, the vibration perception thresholds, VPT, determined with increasing vibration stimuli, the vibration disappearance threshold, VDT, determined with decreasing supraliminal stimuli, and the vibration threshold VT which equals the mean of VPT and VDT. The influence of gender, age, body height, weight and skin temperature at the tested site on thresholds was studied. Retest reliability was tested in 73 children aged 3.3-6.9 years and in 20 volunteers aged 5.2-66.1 years who were also tested for the influence of pretest skin warming on thresholds and for differences between results of the left and right body side. TF, VPT, VDT, VT were closely correlated with each other (Spearman: -0.67<Rs<-0.47; P<0.01). The skin temperature, body side, weight and height did not influence thresholds. In adults, thresholds increased with age and were higher in men above the age of 50 than in women of the same age. Thresholds at the feet were higher than at the hands (Wilcoxon: P<0.001). Retest reliability was high and did not depend on the retest interval. The study provides important normative data for the widespread use of quantitative vibration testing

BACKGROUND AND PURPOSE: Transcranial Doppler sonography (TCD) studies may help to elucidate the nature and role of vascular abnormalities in migraine. Our aim in this study was to evaluate cerebrovascular autoregulative response in migraine patients with and without aura to blood pressure increase using stress TCD. PATIENTS AND METHODS: Using transcranial Doppler ultrasound at rest and during ergometer stress (stress TCD), we studied the changes in mean flow velocities and resistance index (RI) in relation to physical stress in the middle cerebral artery. Fifteen migraine patients without aura, 15 migraine patients with aura, and 15 healthy control subjects were examined. Patients suffered from predominantly unilateral headache and were studied during an attack-free period. The Pourcelot's RI as a measure of cerebrovascular reactivity was calculated by dividing the difference between systolic and diastolic velocity by the systolic velocity. RESULTS: None of the subgroups showed any difference during ergometer exercise with regard to blood pressure, endtidal CO2, heart rate, or mean flow velocity. In all subgroups, sufficient physical stress was achieved. With respect to RI change, migraine patients without aura and healthy controls did not differ (p > 0.05). However, the RI change of migraine patients with aura was significantly lower than the RI change of migraine patients without aura or healthy subjects (p > 0.05). The discrimination analysis showed in addition that RI change (absolute and as a percentage) and mean flow velocity change (as a percentage) could be used as diagnostic variables to detect patients with aura symptoms. CONCLUSION: Differences exist in cerebrovascular reactivity in migraine patients with aura that may contribute to the neurologic disturbances in these patients during attack. We propose that there is disorder of myogenic cerebrovascular autoregulation in migraine patients with aura during headache-free intervals

Microcirculatory vasomotor responses to an alpha-adrenergic agonist and an antagonist were assessed in 11 familial dysautonomia and nine control subjects by laser Doppler flowmetry. Using two iontophoresis machines, blood flow in the midclavicular areas was continuously monitored by two channel laser Doppler flowmeter. Simultaneously, the alpha-antagonist (0.5 mM phentolamine hydrochloride) and a control solution (0.9% saline) were iontophoresed at 200 microA for 15 min. The alpha-agonist (0.5 mM norepinephrine bitartrate) was then iontophoresed (20 microA) to both pretreated areas for progressively longer pulses separated by 3-min observation intervals (15, 30, 60, 90, 120 s). The familial dysautonomia subject group had higher mean baseline perfusion with widely fluctuating baselines, especially on the phentolamine pretreated side (P = 0.03). Saline iontophoresis significantly increased perfusion in the control group, but not in the familial dysautonomia group (ANOVA: P = 0.02 and 0.15, respectively). There was > 100% increase in flow by the end of the saline observation period in seven of nine controls, but in only three of 11 familial dysautonomia subjects. Phentolamine iontophoresis differentiated familial dysautonomia subjects into responders and nonresponders by 7-8 min when all nine control subjects, but only five of 11 familial dysautonomia subjects, had > 200% increase in blood flow. Irrespective of pretreatment type, norepinephrine decreased blood flow in both familial dysautonomia and control groups (ANOVA: P < 0.0001), but the final mean change after saline was greater in the control group, P = 0.02. The final mean changes of flow after phentolamine pretreatment were not different between the two groups and were comparable to the familial dysautonomia group's smaller response after saline pretreatment. Higher baseline perfusion suggests dilation may be intrinsic to familial dysautonomia vasculature. Two populations of familial dysautonomia subjects are noted; those who like controls increase blood flow with iontophoresis of the alpha-antagonist and those who are refractory. In addition, in familial dysautonomia subjects, the microcirculatory constrictive response to alpha-agonist iontophoresis is less than that observed for controls. These data suggest that some familial dysautonomia subjects may have decreased or dysfunctional adrenoceptors as well as decreased innervation

In the etiopathology of tension type headache, vascular and autonomic disorders are discussed. Fifteen patients with chronic tension type headache according to the criteria of the IHS were investigated using the TCD-ergometer-test--a method used to evaluate the myogenic mechanism of cerebrovascular autoregulation--and the results were compared with the findings in fifteen healthy control subjects. The patients' Mean Flow Velocity (TAVmean) and Resistance Index (RI) at rest and after exercise were significantly decreased (p < 0.05). During exercise they normalized. The patients' endtidal pCO2 at rest and during exercise was significantly lower than the corresponding values of the control group (p < 0.05). Regarding blood pressure elevation and heart rate increase during exercise both groups did not differ significantly (p > 0.05). These findings suggest that patients with tension type headache have a diminished vascular tone in the cerebral vessels at rest which is normalised during exercise. The reduced endtidal pCO2 is considered as a physiological response to increase vascular tone via metabolic mechanism of cerebrovascular autoregulation. In conclusion it is suggested that therapeutic procedures which activate sympathetic autonomic nervous function to train cerebral vessels should be more carefully considered